Low-platinum high-stability membrane electrode and preparation method thereof

Abstract

The application discloses a low-platinum high-stability membrane electrode and a preparation method thereof, and belongs to the technical field of fuel cells. X The MXene substrate, platinum nanoparticles and zirconium-doped cerium oxide nanoparticles. The MXene surface is subjected to plasma treatment to form a nitrogen-oxygen co-doped layer, and is vertically arranged to form a porous network structure; the platinum nanoparticles are uniformly dispersed on the MXene surface; the Ce 0.8 Zr 0.2 O2 nanoparticles are embedded between the MXene layers and have a high oxygen vacancy concentration. Through the synergistic effect of the ternary material, high electrochemical activity is maintained while the platinum load is low; the high conductivity of the MXene and the nitrogen-oxygen co-doped layer effectively anchor the platinum nanoparticles, and the stability is significantly improved; the high oxygen vacancy concentration of the Ce 0.8 Zr 0.2 O2 can efficiently capture free radicals, thereby protecting the proton exchange membrane.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, specifically relating to a low-platinum, high-stability membrane electrode and its preparation method. Background Technology

[0002] A fuel cell is a device that directly converts the chemical energy of fuel into electrical energy. Its core component is the membrane electrode assembly (MEA), which typically consists of a proton exchange membrane, a catalyst layer, and a gas diffusion layer. During fuel cell operation, platinum (Pt) in the catalyst layer acts as a key catalytic material, significantly improving the efficiency of hydrogen oxidation and oxygen reduction reactions. However, platinum resources are scarce and expensive; therefore, reducing platinum loading and improving the stability of the MEA have become key areas of focus in fuel cell technology development. Currently, MEA design and fabrication technologies have made some progress, but several problems remain to be solved. For example, how to maintain or even improve catalytic activity and durability while reducing platinum usage, and how to optimize the MEA structure to adapt to different operating conditions. These issues directly affect the overall performance, lifespan, and commercialization of fuel cells.

[0003] Patent application CN111342074A discloses a hydrogen fuel cell. This cell utilizes multiple membrane electrode assemblies and bipolar plates arranged between a first and second electrode plate, and employs porous conduits to achieve uniform distribution of the reactant gases. This design can improve the lifespan and applicability of the fuel cell to some extent, but it does not propose specific technical solutions for reducing platinum loading, leaving room for improvement in cost control. Patent application CN116565246A discloses a fuel cell flow field plate. It improves gas flow characteristics by setting turbulence columns on the base plate, thereby avoiding the accumulation of liquid water in the flow channels. This technical solution can effectively improve the operational stability and efficiency of the fuel cell, but it does not address the optimization of platinum loading and stability improvement of the membrane electrode itself. Therefore, further research is needed to reduce the use of precious metals and extend the lifespan of the membrane electrode.

[0004] In summary, current research on low platinum loading and high stability of membrane electrodes is still insufficient, especially in achieving a significant reduction in platinum loading while maintaining catalytic activity and durability, which remains a significant technical challenge. Summary of the Invention

[0005] One of the objectives of this invention is to provide a low-platinum, high-stability film electrode to solve the problems of high platinum content and poor stability in the prior art.

[0006] The second objective of this invention is to provide a method for preparing a low-platinum, high-stability film electrode, for use in preparing the aforementioned low-platinum, high-stability film electrode.

[0007] In one aspect, a low-platinum, high-stability membrane electrode comprises a proton exchange membrane, a catalyst layer, and a gas diffusion layer stacked sequentially.

[0008] The catalyst layer is composed of Ti3C2T X MXene matrix, platinum nanoparticles and zirconium-doped cerium oxide (Ce) 0.8 Zr 0.2 The composition is O2 nanoparticles, and the mass ratio of the three components is (68-72):(23-27):5;

[0009] The Ti3C2T X The surface of MXene is treated with plasma to form a nitrogen-oxygen co-doped layer with a zeta potential of -30 to -40 mV, and vertically oriented to form a porous network structure with a pore size of 50-200 nm.

[0010] The platinum nanoparticles are uniformly dispersed on the MXene surface, with a particle size of 2-3 nm; the Ce... 0.8 Zr 0.2 O2 nanoparticles with a particle size of 5-8 nm are embedded in the MXene layers, and their oxygen vacancy concentration is ≥10. 21 cm -3 Oxygen storage capacity ≥750 μmol O2 / g.

[0011] Furthermore, the Ti3C2T X The raw material for preparing MXene is Ti3AlC2 powder, which has an Al content of 7.5-8.5 wt%, a particle size of 1-3 μm, and a purity of ≥99%.

[0012] Furthermore, in the nitrogen-oxygen co-doped layer, the nitrogen content on the MXene surface is 2.5-3.5 at%, the oxygen content is 17-19 at%, and Ti-N bonds and Ti-O bonds are formed on the surface.

[0013] Furthermore, the Ti3C2T X MXene has a sheet thickness of 1-3nm and a sheet diameter of 200-500nm.

[0014] Furthermore, the catalyst layer has a porosity of 40%–50% and a gas permeability of 1.5–2.5 × 10⁻⁶. -12 m 2 The proton conductivity is 0.08-0.12 S / cm.

[0015] Furthermore, the proton exchange membrane is a perfluorosulfonic acid membrane with a thickness of 50±5μm and an ion exchange capacity of 1.0±0.05mmol / g.

[0016] Furthermore, the gas diffusion layer is made of carbon paper with a porosity of 70%–80% and a thickness of 150–250 μm.

[0017] Furthermore, the loading of the platinum nanoparticles is controlled by an electrophoretic deposition process, and the final mass percentage of platinum in the catalyst layer is 24%-26%.

[0018] Furthermore, the Ce 0.8 Zr 0.2 The oxygen storage capacity of O2 nanoparticles is 750-850 μmol O2 / g, and the oxygen vacancy concentration is 10. 21 -10 22 cm -3 .

[0019] A method for preparing a low-platinum, high-stability film electrode includes the following steps:

[0020] (a) MXene preparation: Ti3AlC2 powder was etched with hydrofluoric acid and washed into the eluent. A concentration of <1 ppm yielded an MXene dispersion;

[0021] (b) MXene functionalization: The MXene dispersion was subjected to radio frequency plasma treatment and ammonia gas was introduced to achieve nitrogen-oxygen co-doping;

[0022] (c)Ce 0.8 Zr 0.2 O2 nanoparticle synthesis: Ammonia water was added dropwise to a mixed solution of cerium ammonium nitrate and zirconium nitrate to precipitate the precipitate, followed by hydrothermal crystallization and drying to obtain Ce. 0.8 Zr 0.2 O2 powder;

[0023] (d) Catalyst ink formulation: Mixed functionalized MXene dispersion, Ce 0.8 Zr 0.2 O2 powder, chloroplatinic acid solution and dispersing agent are ultrasonically dispersed evenly;

[0024] (e) Electrophoretic deposition: Under a nitrogen atmosphere, catalyst ink is loaded onto the surface of a proton exchange membrane to form a catalyst layer;

[0025] (f) Heat treatment reduction: platinum is reduced by low-temperature heat treatment in a hydrogen-containing atmosphere;

[0026] (g) Hot-press bonding: The proton exchange membrane with the catalyst layer deposited is hot-pressed together with the gas diffusion layer to obtain a low-platinum, high-stability membrane electrode.

[0027] Furthermore, in step (a), the hydrofluoric acid concentration is ≤10wt%, the etching reaction temperature is 40°C, the reaction time is 22-26 hours, and the stirring rate is 250-350rpm; the concentration of the MXene dispersion is adjusted to 4.8-5.2mg / mL after washing.

[0028] Furthermore, in step (b), the parameters for radio frequency plasma treatment are: ammonia flow rate 50±5 sccm, N2:H2 volume ratio in ammonia (3.8-4.2):(0.9-1.1), radio frequency power 100W, radio frequency 13.56±0.01MHz, cavity pressure 20±2Pa, and treatment time 60 seconds.

[0029] Furthermore, in step (c), the molar ratio of cerium ammonium nitrate to zirconium nitrate is 4:1, the total metal ion concentration of the mixed solution is 0.45-0.55M; the ammonia droplet acceleration rate is 1.8-2.2 mL / min, the final pH of the droplet is 9.5±0.1; the hydrothermal crystallization temperature is 175-185°C, the holding time is 11-13 hours; and the drying conditions are vacuum drying at 59.5-60.5°C for 11.5-12.5 hours.

[0030] Furthermore, in step (d), the solid content of the catalyst ink is 1.0-1.5 wt%, and the pH is 3.0-4.0; the dispersing agent is polyvinylpyrrolidone, which is added at an amount of 0.05-0.15 wt% of the total ink mass, and has a molecular weight of 9500-10500; the ultrasonic dispersion power is 180-220 W, and the total dispersion time is 25-35 minutes.

[0031] Furthermore, in step (d), ascorbic acid is added to the chloroplatinic acid solution, the molar ratio of ascorbic acid to chloroplatinic acid is 2:1, and the pH of the solution is 3.0-4.0.

[0032] Furthermore, in step (e), the conditions for electrophoretic deposition are: oxygen content <50ppm in a nitrogen atmosphere, deposition temperature 23-27°C, applied DC voltage 1.4-1.6V, and deposition time 115-125 seconds.

[0033] Furthermore, in step (f), the heat treatment atmosphere is a 5% H2 / Ar mixture, the heating rate is 1.5-2.5°C / min, the holding temperature is 80°C, the holding time is 30 minutes, and the temperature during the heat treatment does not exceed 100°C.

[0034] Furthermore, in step (g), the conditions for hot pressing are: temperature 125-135°C, pressure 1.8-2.2MPa, and hot pressing time 85-95 seconds.

[0035] Furthermore, in step (a), the Ti3AlC2 powder is etched and then separated by centrifugal washing at a speed of 9800-10200 rpm and a washing frequency of 4-6 times.

[0036] Furthermore, after step (f), the thickness of the catalyst layer is 8-9 μm.

[0037] The beneficial effects of this invention are:

[0038] (1) This invention constructs MXene-Ce 0.8 Zr 0.2 The O2-platinum ternary synergistic catalytic system breaks through the traditional constraint between platinum loading and electrochemical activity. The highly conductive network and large specific surface area of ​​the MXene support provide abundant active sites for platinum nanoparticles, Ce... 0.8 Zr 0.2 The dynamic oxygen vacancy of O2 promotes reactant adsorption, and the nitrogen-oxygen co-doping layer optimizes the electron transport path. The synergistic effect of these three factors achieves high electrochemical activity under ultra-low platinum loading, solving the problem of insufficient activity in low-platinum systems. In addition, the synergistic effect of the ternary catalytic system enables the membrane electrode to maintain high activity while significantly extending its service life.

[0039] (2) This invention employs plasma functionalization technology to construct a nitrogen-oxygen co-doped layer on the surface of MXene, which significantly enhances the adsorption capacity of the support for platinum nanoparticles. Through the strong interaction between the surface functional groups and platinum, this structure effectively suppresses the dissolution, migration, and aggregation of platinum during operation, thereby greatly improving the structural stability of the catalyst.

[0040] (3) This invention will use Ce 0.8 Zr 0.2 Introducing O2 material into the fuel cell catalyst layer utilizes its high oxygen vacancy concentration to achieve efficient capture of free radicals in the membrane electrode assembly (MEA). This design allows free radical scavenging and catalytic reactions to occur synergistically in the same space, preventing free radicals from attacking the proton exchange membrane, solving the membrane degradation problem, and resolving the contradiction between free radical scavenging and proton conduction in existing technologies.

[0041] (4) This invention achieves the deposition of MXene, platinum and Ce through plasma-assisted electrophoretic co-deposition process. 0.8 Zr 0.2 The assembly of O2 forms a ternary catalytic structure with a specific spatial distribution. In this structure, the Ti atoms of MXene undergo d-orbital hybridization with platinum, lowering the d-band center of platinum; Ce... 0.8 Zr 0.2O2 oxygen vacancies dynamically repair film damage; the nitrogen-oxygen co-doped layer acts as an electron bridge to enhance interfacial coupling. This nonlinear synergistic effect not only improves the oxygen reduction reaction kinetics but also enhances the stability of the electrode under high current density and humidity fluctuation conditions.

[0042] (5) This invention uses an aqueous preparation system throughout, avoiding the use of toxic organic solvents. Hydrofluoric acid is safely neutralized in a closed system, and the operation process complies with industrial safety standards. This green preparation process not only reduces production risks but also ensures the integrity of the material structure, making it suitable for large-scale industrial production.

[0043] (6) The catalyst layer of the present invention has an optimized porous network structure, which achieves a balance between gas transport, proton conduction and electron conduction. The vertical orientation of MXene forms a highly efficient reactant transport channel while maintaining sufficient proton conduction capacity, effectively solving the performance degradation problem caused by mass transfer limitation in low platinum systems. Detailed Implementation

[0044] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0045] In some embodiments, a low-platinum, high-stability membrane electrode includes a proton exchange membrane, a catalyst layer, and a gas diffusion layer stacked sequentially.

[0046] The catalyst layer is composed of Ti3C2T X MXene matrix, platinum nanoparticles and zirconium-doped cerium oxide (Ce) 0.8 Zr 0.2 The composition is O2 nanoparticles, and the mass ratio of the three components is (68-72):(23-27):5;

[0047] By precisely proportioning the ternary components, an optimal balance of activity, conductivity, and stability is achieved. MXene provides a highly conductive network and anchoring sites, platinum provides the catalytic active centers, and Ce... 0.8 Zr 0.2 O2 is responsible for scavenging free radicals and protecting the film structure. A specific mass ratio ensures a non-linear synergistic effect among the three components, avoiding performance degradation caused by imbalances in the proportion of a single component, and maintaining high activity and long lifetime even with low platinum loading.

[0048] The Ti3C2T X The surface of MXene is treated with plasma to form a nitrogen-oxygen co-doped layer with a zeta potential of -30 to -40 mV, and vertically oriented to form a porous network structure with a pore size of 50-200 nm.

[0049] Plasma treatment induces a nitrogen-oxygen co-doped layer on the MXene surface, altering its surface chemistry and enhancing its electronegativity. This surface modification prevents MXene sheet stacking, maintaining a porous structure, and simultaneously enhances the adsorption capacity for platinum precursors, achieving uniform dispersion of platinum nanoparticles and providing a structural basis for ultra-low platinum loading. The vertically oriented structure significantly improves gas diffusion efficiency, reduces oxygen transport resistance, and maintains sufficient catalyst-reactant contact area, effectively addressing the mass transfer limitation problem under low platinum loading and improving electrode performance at high current densities.

[0050] The platinum nanoparticles are uniformly dispersed on the MXene surface, with a particle size of 2-3 nm; the Ce... 0.8 Zr 0.2 O2 nanoparticles with a particle size of 5-8 nm are embedded in the MXene layers, and their oxygen vacancy concentration is ≥10. 21 cm -3 Oxygen storage capacity ≥750 μmol O2 / g.

[0051] The abundant anchoring sites provided by the nitrogen-oxygen co-doped layer on the MXene surface stabilize the platinum nanoparticles within the optimal particle size range, achieving high dispersion. This particle size range gives the platinum particles an optimal electronic structure, optimizes the oxygen molecule adsorption energy, and the high conductivity and mechanical strength of MXene effectively inhibit the dissolution and migration of platinum particles, significantly improving catalyst stability. 0.8 Zr 0.2 Oxygen vacancies in O2 serve as free radical scavenging sites, effectively scavenging hydroxyl radicals generated during fuel cell operation. A specific particle size range ensures a balance between high specific surface area and oxygen vacancy stability, while high oxygen vacancy concentration provides sufficient free radical scavenging capacity, fundamentally solving the membrane degradation problem and extending electrode lifespan.

[0052] In some embodiments, the Ti3C2T X The raw material for preparing MXene is Ti3AlC2 powder, which has an Al content of 7.5-8.5 wt%, a particle size of 1-3 μm, and a purity of ≥99%.

[0053] As a precursor to the MAX phase, the Al content of Ti3AlC2 directly affects the etching effect and MXene yield, while the particle size affects the etching uniformity, and the purity determines the occurrence of side reactions. Selecting Ti3AlC2 powder with specific parameter ranges ensures the controllability of the etching process and the stability of MXene product quality, providing a reliable foundation for subsequent functionalization and catalyst layer preparation.

[0054] In some embodiments, in the nitrogen-oxygen co-doped layer, the nitrogen content on the MXene surface is 2.5-3.5 at%, the oxygen content is 17-19 at%, and Ti-N bonds and Ti-O bonds are formed on the surface.

[0055] Precise control of nitrogen and oxygen content directly affects the conductivity and stability of MXene, as well as its interaction with platinum particles. The formation of Ti-N and Ti-O bonds is direct evidence of nitrogen and oxygen doping. The formation of these chemical bonds alters the surface electronic structure of MXene, enhances its stability in acidic environments, and provides ideal anchoring sites for platinum particles.

[0056] In some embodiments, the Ti3C2T X MXene has a sheet thickness of 1-3nm and a sheet diameter of 200-500nm.

[0057] The thickness of the lamellar sheets affects the conductivity and mechanical strength of MXene, while the sheet diameter affects its dispersion and stacking behavior. A specific range of lamellar thickness and sheet diameter balances the conductivity, mechanical strength, and dispersion stability of MXene, providing an ideal support for constructing high-performance catalyst layers and ensuring the realization of vertical orientation and the stability of the pore structure.

[0058] In some embodiments, the porosity of the catalyst layer is 40%–50%, and the gas permeability is 1.5–2.5 × 10⁻⁶. -12 m 2 The proton conductivity is 0.08-0.12 S / cm.

[0059] The catalyst layer must simultaneously meet the requirements of electron conduction, proton conduction, and gas transport. A specific range of porosity, gas permeability, and proton conductivity achieves an optimal balance of three-phase mass transfer, ensuring efficient transport of reactants to active sites while guaranteeing effective proton and electron conduction, enabling the membrane electrode to maintain high efficiency even at high current densities.

[0060] In some embodiments, the proton exchange membrane is a perfluorosulfonic acid membrane with a thickness of 50±5 μm and an ion exchange capacity of 1.0±0.05 mmol / g.

[0061] Membrane thickness affects proton conduction and mechanical stability, while ion exchange capacity determines proton conductivity and swelling behavior. Perfluorosulfonic acid membranes with specific parameter ranges ensure appropriate proton conductivity and sufficient mechanical strength. When used in conjunction with the catalyst layer of this invention, they achieve good interfacial contact, avoiding performance loss due to membrane performance mismatch.

[0062] In some embodiments, the gas diffusion layer is carbon paper with a porosity of 70% to 80% and a thickness of 150 to 250 μm.

[0063] The porosity of the gas diffusion layer affects gas diffusion and water discharge, while the thickness balances gas diffusion and mechanical support. Carbon paper with specific parameter ranges optimizes reactant supply and product discharge, ensuring stable electrode operation under various conditions and avoiding water flooding or gas starvation at high current densities.

[0064] In some embodiments, the loading of the platinum nanoparticles is controlled by an electrophoretic deposition process, and the final mass percentage of platinum in the catalyst layer is 24%-26%.

[0065] A specific mass percentage corresponds to an ultra-low platinum loading, representing a balance between low platinum content and high activity. Electrophoretic deposition, through precise control of process parameters, achieves accurate regulation of the platinum loading, ensuring a balance between ultra-low platinum loading and high utilization, significantly reducing electrode costs while maintaining high electrochemical activity.

[0066] In some embodiments, the Ce 0.8 Zr 0.2 The oxygen storage capacity of O2 nanoparticles is 750-850 μmol O2 / g, and the oxygen vacancy concentration is 10. 21 -10 22 cm -3 .

[0067] The specific range of oxygen storage capacity and oxygen vacancy concentration ensures sufficient free radical scavenging capability without affecting the electrochemical performance of the catalyst layer. This optimized free radical scavenging capability effectively protects the proton exchange membrane, extends electrode lifespan, and solves a key lifespan issue in the commercial application of fuel cells.

[0068] A method for preparing a low-platinum, high-stability film electrode includes the following steps:

[0069] (a) MXene preparation: Ti3AlC2 powder was etched with hydrofluoric acid and washed into the eluent. A concentration of <1 ppm yielded an MXene dispersion;

[0070] (b) MXene functionalization: The MXene dispersion was subjected to radio frequency plasma treatment and ammonia gas was introduced to achieve nitrogen-oxygen co-doping;

[0071] (c)Ce 0.8 Zr 0.2 O2 nanoparticle synthesis: Ammonia water was added dropwise to a mixed solution of cerium ammonium nitrate and zirconium nitrate to precipitate the precipitate, followed by hydrothermal crystallization and drying to obtain Ce. 0.8 Zr 0.2 O2 powder;

[0072] (d) Catalyst ink formulation: Mixed functionalized MXene dispersion, Ce 0.8 Zr0.2 O2 powder, chloroplatinic acid solution and dispersing agent are ultrasonically dispersed evenly;

[0073] (e) Electrophoretic deposition: Under a nitrogen atmosphere, catalyst ink is loaded onto the surface of a proton exchange membrane to form a catalyst layer;

[0074] (f) Heat treatment reduction: platinum is reduced by low-temperature heat treatment in a hydrogen-containing atmosphere;

[0075] (g) Hot-press bonding: The proton exchange membrane with the catalyst layer deposited is hot-pressed together with the gas diffusion layer to obtain a low-platinum, high-stability membrane electrode.

[0076] In some embodiments, in step (a), the concentration of hydrofluoric acid is ≤10wt%, the etching reaction temperature is 40°C, the reaction time is 22-26 hours, and the stirring rate is 250-350rpm; the concentration of the MXene dispersion is adjusted to 4.8-5.2mg / mL after washing.

[0077] Etching conditions within a specific parameter range ensured operational safety while yielding a high-quality MXene dispersion. These parameters worked together to achieve complete removal of the Al layer and integrity of the MXene structure, providing a high-quality raw material for subsequent functionalization.

[0078] In some embodiments, the parameters for the radio frequency plasma treatment in step (b) are: ammonia flow rate 50±5 sccm, N2:H2 volume ratio in ammonia (3.8-4.2):(0.9-1.1), radio frequency power 100W, radio frequency frequency 13.56±0.01MHz, cavity pressure 20±2Pa, and treatment time 60 seconds.

[0079] Plasma treatment with specific parameters enabled precise control of nitrogen and oxygen doping on the MXene surface, forming an ideal nitrogen-oxygen co-doped layer. This surface modification optimized the surface chemistry of MXene, enhanced its stability in acidic environments and its adsorption capacity for platinum precursors, and provided an ideal surface for the uniform dispersion of platinum nanoparticles.

[0080] In some embodiments, in step (c), the molar ratio of cerium ammonium nitrate to zirconium nitrate is 4:1, the total metal ion concentration of the mixed solution is 0.45-0.55M; the ammonia droplet acceleration rate is 1.8-2.2 mL / min, the droplet endpoint pH is 9.5±0.1; the hydrothermal crystallization temperature is 175-185°C, the holding time is 11-13 hours; and the drying conditions are vacuum drying at 59.5-60.5°C for 11.5-12.5 hours.

[0081] A specific molar ratio ensures C Z The accuracy of stoichiometry, and the specific metal ion concentrations, balance precipitation homogeneity and particle size. These parameters work together to ensure C Z The high crystallinity and phase purity of the Ce provide a material basis for achieving high oxygen vacancy concentrations. A specific dropping acceleration rate ensures the controllability of the precipitation reaction, avoiding particle agglomeration caused by local supersaturation; a specific endpoint pH ensures complete precipitation and uniform particle size. These parameters work together to provide a high-quality precursor for subsequent hydrothermal crystallization, ensuring the high crystallinity of Ce. 0.8 Zr 0.2 The high performance of O2. Specific hydrothermal temperatures and holding times ensure precise control of grain size and the formation of oxygen vacancies. These parameters work together to achieve C Z Its high crystallinity and high oxygen vacancy concentration provide effective sites for free radical scavenging.

[0082] In some embodiments, in step (d), the solid content of the catalyst ink is 1.0-1.5 wt%, and the pH is 3.0-4.0; the dispersing agent is polyvinylpyrrolidone, which is added at an amount of 0.05-0.15 wt% of the total ink mass, and has a molecular weight of 9500-10500; the ultrasonic dispersion power is 180-220 W, and the total dispersion time is 25-35 minutes.

[0083] A specific solids content balances deposition efficiency with ink stability, while a specific pH ensures the stability of the platinum precursor and the dispersibility of MXene. These parameters work together to ensure the stability of the electrophoretic deposition process and the uniformity of the catalyst layer, providing a foundation for constructing a high-performance catalyst layer.

[0084] In some embodiments, in step (d), ascorbic acid is added to the chloroplatinic acid solution, the molar ratio of ascorbic acid to chloroplatinic acid is 2:1, and the pH of the solution is 3.0-4.0.

[0085] A specific ratio of ascorbic acid, acting as a mild reducing agent, controls the degree of reduction of the platinum precursor; a specific pH maintains the stability of the platinum precursor. These parameters work together to control the initial core size of the platinum particles, ensuring the acquisition of highly dispersed platinum nanoparticles.

[0086] In some embodiments, in step (e), the conditions for electrophoretic deposition are: oxygen content <50ppm in a nitrogen atmosphere, deposition temperature 23-27°C, applied DC voltage 1.4-1.6V, and deposition time 115-125 seconds.

[0087] Specific electrophoresis conditions ensured the presence of MXene, platinum, and C. Z The simultaneous co-deposition of the catalyst layer resulted in a ternary structure with nanoscale spacing. This precise deposition control enabled the accurate construction of the catalyst layer's microstructure, which is the core process for maximizing the synergistic effect of the materials.

[0088] In some embodiments, in step (f), the heat treatment atmosphere is a 5% H2 / Ar mixture, the heating rate is 1.5-2.5°C / min, the holding temperature is 80°C, the holding time is 30 minutes, and the temperature during the heat treatment does not exceed 100°C.

[0089] The heat treatment conditions ensured the complete reduction of platinum while protecting the structural integrity of MXene. This gentle reduction process achieved a perfect balance between the reduction of the active component and the protection of the support, thus guaranteeing the formation of a highly active catalyst layer.

[0090] In some embodiments, the hot-pressing conditions in step (g) are: temperature 125-135°C, pressure 1.8-2.2 MPa, and hot-pressing time 85-95 seconds.

[0091] Specific hot-pressing conditions ensure good contact between the membrane and the catalyst layer while protecting the structural integrity of the catalyst layer. This optimized interface treatment reduces contact resistance and improves overall electrode performance.

[0092] In some embodiments, in step (a), the Ti3AlC2 powder is etched and then separated by centrifugal washing at a speed of 9800-10200 rpm and a washing frequency of 4-6 times.

[0093] In some embodiments, after step (f), the thickness of the catalyst layer is 8-9 μm, and the actual platinum loading deviates from the theoretical value by ≤±5% as detected by inductively coupled plasma mass spectrometry.

[0094] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0095] Example 1

[0096] This embodiment provides a low-platinum, high-stability film electrode, which is prepared through the following steps:

[0097] Preparation and functionalization of S1 and MXene carriers

[0098] 10 g of Ti3AlC2 powder (particle size 2.0 ± 0.2 μm, Al content 8 wt%, purity 99.0%) was added to 150 mL of 10 wt% hydrofluoric acid (HF, 48%) aqueous solution and mechanically stirred at 300 rpm for 24 hours at 40°C to obtain Ti3C2T X MXene;

[0099] After the reaction, the sample was washed by centrifugation with deionized water (10,000 rpm, 5 times), and deionized water was added to prepare an MXene dispersion (concentration 5 mg / mL). 100 mL of the MXene dispersion was placed in a plasma reaction chamber, and 50 sccm of ammonia gas (N2:H2=4:1) was introduced. 100 W of radio frequency power (13.56 MHz) was applied, the chamber pressure was 20 Pa, and the treatment lasted for 60 seconds to obtain functionalized MXene.

[0100] S2, Ce 0.8 Zr 0.2 Synthesis of O2 nanoparticles

[0101] Prepare 100 mL of a mixed solution of 0.50 M cerium ammonium nitrate ((NH4)2Ce(NO3)6, 99.9%) and 0.125 M zirconium nitrate (ZrO(NO3)2, 99.5%) (Ce:Zr molar ratio = 4:1); in a 60 °C water bath, add 1 M ammonia water dropwise at a rate of 2 mL / min until pH = 9.5, and continue stirring for 2 hours; collect the precipitate by centrifugation, wash with deionized water until neutral; transfer the precipitate to a polytetrafluoroethylene-lined reactor, add 150 mL of deionized water, and incubate at 180 °C for 12 hours; after cooling, vacuum dry at 60 °C for 12 hours to obtain Ce. 0.8 Zr 0.2 O2 nanoparticles;

[0102] S3, Catalyst Ink Formulation

[0103] Take 20 mL of functionalized MXene dispersion (5 mg / mL) and add Ce 0.8 Zr 0.2 0.5 mg of O2 nanoparticles were ultrasonically dispersed at 200 W for 30 minutes; then 5 mL of chloroplatinic acid (H2PtCl6, 5 mM, pH=3.5) solution was added, and ultrasonication was continued for 10 minutes; 0.1 mg of polyvinylpyrrolidone was added, and after mixing, the catalyst ink was obtained.

[0104] S4, Membrane Electrode Assembly

[0105] Commercial Nafion membranes were selected, cleaned by boiling in deionized water, and then dried in a vacuum drying oven at 60°C. The Nafion membrane was used as the cathode, and a platinum sheet was used as the anode. The membranes were immersed in catalyst ink. Under a nitrogen atmosphere and a temperature of 25°C, a DC voltage of 1.50V was applied, and the deposition time was 120 seconds. The deposited membrane was then heat-treated in an H2 / Ar mixed gas (5% H2) at a rate of 2°C / min to 80°C for 30 minutes.

[0106] The prepared membrane electrode was hot-pressed together with a carbon paper-based gas diffusion layer at a temperature of 130°C, a pressure of 2 MPa, and a time of 90 seconds to obtain a low-platinum, high-stability membrane electrode.

[0107] Example 2

[0108] The difference between this embodiment and Embodiment 1 is that the "MXene dispersion plasma treatment time" is changed to "40 seconds".

[0109] The remaining raw materials and preparation process are the same as in Example 1.

[0110] Example 3

[0111] The difference between this embodiment and Embodiment 1 is that Ce 0.8 Zr 0.2 The O2 doping ratio was adjusted to 8%.

[0112] The remaining raw materials and preparation process are the same as in Example 1.

[0113] Example 4

[0114] The difference between this embodiment and Embodiment 1 is that Ce 0.8 Zr 0.2 The O2 doping ratio was adjusted to 3%.

[0115] The remaining raw materials and preparation process are the same as in Example 1.

[0116] Example 5

[0117] The difference between this embodiment and Embodiment 1 is that the “electrophoretic deposition voltage” is changed to “1 V”.

[0118] The remaining raw materials and preparation process are the same as in Example 1.

[0119] Example 6

[0120] The difference between this embodiment and Embodiment 1 is that the "heat treatment temperature" is changed to "120°C".

[0121] The remaining raw materials and preparation process are the same as in Example 1.

[0122] Example 7

[0123] The difference between this embodiment and Embodiment 1 is that the "ammonia flow rate" is changed to "40 sccm".

[0124] The remaining raw materials and preparation process are the same as in Example 1.

[0125] Example 8

[0126] The difference between this embodiment and Embodiment 1 is that the "pH of chloroplatinic acid solution" is changed to "2.0".

[0127] The remaining raw materials and preparation process are the same as in Example 1.

[0128] Example 9

[0129] The difference between this embodiment and Embodiment 1 is that the "hydrothermal temperature" is changed to "160℃".

[0130] The remaining raw materials and preparation process are the same as in Example 1.

[0131] Example 10

[0132] The difference between this embodiment and Embodiment 1 is that the "ultrasonic dispersion power" is changed to "150 W".

[0133] The remaining raw materials and preparation process are the same as in Example 1.

[0134] Comparative Example 1

[0135] The difference between this comparative example and Example 1 is that Ce is not added. 0.8 Zr 0.2 O2, using only the MXene-Pt catalyst system. The specific implementation steps are as follows: when preparing the catalyst ink, only the functionalized MXene dispersion and chloroplatinic acid solution are mixed, omitting Ce. 0.8 Zr 0.2 The addition of O2.

[0136] The remaining raw materials and preparation process are the same as in Example 1.

[0137] Comparative Example 2

[0138] The difference between this comparative example and Example 1 is that a commercially available Pt / C catalyst (platinum supported at 0.4 mg / cm³) was used. 2 The specific implementation steps are as follows: Commercial Pt / C (20 wt%) is mixed with a Nafion solution, and a catalyst layer is formed on a Nafion membrane by spraying, with a platinum loading of 0.40 mg / cm³. 2 .

[0139] The remaining raw materials and preparation process are the same as in Example 1.

[0140] Comparative Example 3

[0141] The difference between this comparative example and Example 1 is that MXene was not treated with plasma. Specifically, the plasma treatment in Example 1 was omitted, and the original MXene dispersion was used directly for subsequent operations.

[0142] The remaining raw materials and preparation process are the same as in Example 1.

[0143] Comparative Example 4

[0144] The difference between this comparative example and Example 1 is that Ce 0.8 Zr 0.2 O2 is physically mixed with MXene and platinum. The specific steps are as follows: first, prepare the MXene-Pt catalyst and Ce... 0.8 Zr 0.2 The O2 dispersion is then simply mixed to form ink, omitting the plasma treatment and electrophoretic co-deposition steps.

[0145] The remaining raw materials and preparation process are the same as in Example 1.

[0146] Comparative Example 5

[0147] The difference between this comparative example and Example 1 is that chitosan is used as a binder instead of the plasma functionalization of the present invention. Specifically, 1 wt% chitosan quaternary ammonium salt (molecular weight 200,000 ± 10,000) is added to the catalyst ink, omitting the plasma treatment step.

[0148] The remaining raw materials and preparation process are the same as in Example 1.

[0149] Comparative Example 6

[0150] The difference between this comparative example and Example 1 is that a conventional carbon support (Vulcan XC-72) was used instead of MXene. The specific implementation steps were as follows: a Pt / C catalyst was prepared using an impregnation reduction method, with a platinum loading of 0.08 mg / cm³. 2 Then with Ce 0.8 Zr 0.2 O2 physical mixing.

[0151] The remaining raw materials and preparation process are the same as in Example 1.

[0152] Performance testing

[0153] According to GB / T 20042.5-2024, "Proton Exchange Membrane Fuel Cells - Part 5: Membrane Electrode Test Methods", the electrochemical performance and durability of the low-platinum, high-stability membrane electrodes obtained in various embodiments and comparative examples of this application were tested; the results are shown in Table 1.

[0154] Table 1

[0155]

[0156] (Comparative Examples 2 and 5 became invalid after 3000 hours of testing and could not complete the 30000-hour test.)

[0157] As shown in Table 1, Example 1 performed best in all test items, with its mass activity being significantly higher than that of commercial Pt / C (0.3 A / m). This breaks the technical prejudice that "low platinum loading inevitably leads to decreased activity." This is due to MXene-Ce 0.8 Zr 0.2 Synergistic effect of O2-platinum ternary system: MXene's high conductivity and large specific surface area provide abundant active sites; Ce 0.8 Zr 0.2 Oxygen vacancy dynamics in O2 promote reactant adsorption; nitrogen-oxygen co-doped layers optimize electron transport pathways.

[0158] In Example 2, shortening the plasma treatment time resulted in a higher interfacial energy barrier between MXene and platinum, leading to a decrease in the uniformity of platinum nanoparticle distribution and agglomeration in some areas. After accelerated stress testing, the ECSA retention rate dropped to 75%, indicating that insufficient plasma treatment time affected catalyst stability. In Example 3, Ce... 0.8 Zr 0.2 Increasing the O2 ratio leads to a decrease in gas diffusion efficiency. The peak power density drops to 1.1 W / cm³. 2 This indicates that Ce 0.8 Zr 0.2 An excessively high O2 ratio can block gas transport channels, affecting the overall performance of the electrode. In Example 4, Ce... 0.8 Zr 0.2 With a reduced O2 ratio, the free radical scavenging capacity became insufficient, and the fluoride ion release rate (FRR) increased to 10 μg / h. After a 30,000-hour long-life test, the power density decay rate reached 18%, demonstrating that Ce... 0.8 Zr 0.2 A low O2 ratio fails to effectively protect the proton exchange membrane. In Example 5, reducing the deposition voltage resulted in uneven catalyst layer thickness and localized voids, leading to performance degradation. In Example 6, increasing the heat treatment temperature partially oxidized MXene to TiO2, decreasing conductivity and causing an increase in platinum nanoparticle size, reducing the mass activity to 0.65 A / m. This indicates that temperatures exceeding 100°C will damage the MXene structure and affect electrode performance. In Example 7, reducing the ammonia flow rate weakened the plasma treatment effect and reduced the nitrogen content on the MXene surface, leading to an incomplete nitrogen-oxygen co-doped layer and decreased platinum nanoparticle adsorption. The mass activity was 0.78 A / m. This demonstrates the crucial impact of ammonia flow rate on the doping effect. In Example 8, decreasing the pH of the chloroplatinic acid solution accelerated the hydrolysis of the platinum precursor, leading to the formation of large platinum particles and agglomeration. ECSA decreased to 60 μm. 2 / g, confirming the crucial controlling role of pH value on platinum particle size. In Example 9, after the hydrothermal temperature decreased, Ce 0.8 Zr 0.2 The decrease in O2 crystallinity and the reduction in oxygen vacancy concentration resulted in an increase in FRR to 6 μg / h during long-term operation testing, demonstrating the effect of hydrothermal temperature on Ce. 0.8 Zr 0.2 The impact of O2 performance. In Example 10, after the ultrasonic power was reduced, the MXene sheets were not sufficiently dispersed and agglomeration occurred, resulting in a decrease in the performance consistency of single cells.

[0159] The membrane electrode of Comparative Example 1 achieved an FRR of 18.5 μg / h after 10,000 hours of constant voltage operation at 0.6 V. However, after 5,000 cycles of accelerated stress testing, the ECSA retention rate was only 65%, indicating a lack of Ce. 0.8 Zr 0.2 O2 accelerates membrane degradation, which in turn triggers catalyst dissolution. The initial mass activity of the membrane electrode in Comparative Example 2 was 0.30 A / m. After 3000 hours of operation, the power density decreased by 35%, while in Example 1 it decreased by only 8.2% after 30,000 hours. This highlights the advantage of this invention in achieving high stability with low platinum content. Comparative Example 3, without plasma treatment, exhibited poor stability in an acidic environment, and the platinum nanoparticles were unevenly distributed, resulting in severe agglomeration. Electrochemical testing showed that the ECSA retention rate was only 55%, confirming the crucial role of plasma treatment in the stability of MXene and platinum dispersion. Comparative Example 4, physical mixing led to uneven component distribution, and Ce... 0.8 Zr 0.2 The increased spacing between O2 and platinum particles prevents effective synergy, leading to a decline in electrochemical performance. This confirms the importance of precise nanoscale assembly for synergistic effects. In Comparative Example 5, chitosan quaternary ammonium salts undergo protonation in acidic environments, resulting in decreased proton conductivity. Simultaneously, the high molecular chains of chitosan hinder reactant transport, significantly deteriorating high current density performance. Furthermore, chitosan degrades during long-term operation, producing byproducts that clog pores, resulting in a 25% power density decay after 3000 hours. In Comparative Example 6, the carbon support is prone to corrosion at high potentials, especially during start-stop cycles. Accelerated stress testing caused catalyst layer structure collapse, with ECSA retention of only 40%. This indicates that traditional carbon supports cannot meet the requirements for high-stability electrodes with low platinum content.

[0160] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A low-platinum, high-stability film electrode, characterized in that, It includes a proton exchange membrane, a catalyst layer, and a gas diffusion layer stacked in sequence; The catalyst layer is composed of Ti3C2T X MXene matrix, platinum nanoparticles and Ce 0.8 Zr 0.2 The composition is O2 nanoparticles, and the mass ratio of the three components is (68-72):(23-27):5; The Ti3C2T X The surface of MXene is treated with plasma to form a nitrogen-oxygen co-doped layer with a zeta potential of -30 to -40 mV, and vertically oriented to form a porous network structure with a pore size of 50-200 nm. The platinum nanoparticles are uniformly dispersed on the MXene surface, with a particle size of 2-3 nm; the Ce... 0.8 Zr 0.2 O2 nanoparticles with a particle size of 5-8 nm are embedded in the MXene layers, and their oxygen vacancy concentration is ≥10. 21 cm -3 Oxygen storage capacity ≥750 μmol O2 / g.

2. The low-platinum, high-stability film electrode according to claim 1, characterized in that, The Ti3C2T X The raw material for preparing MXene is Ti3AlC2 powder, which has an Al content of 7.5-8.5 wt%, a particle size of 1-3 μm, and a purity of ≥99%. The Ti3C2T X MXene has a sheet thickness of 1-3nm and a sheet diameter of 200-500nm.

3. The low-platinum, high-stability film electrode according to claim 1, characterized in that, In the nitrogen-oxygen co-doped layer, the nitrogen content on the MXene surface is 2.5-3.5 at%, the oxygen content is 17-19 at%, and Ti-N and Ti-O bonds are formed on the surface.

4. The low-platinum, high-stability film electrode according to claim 1, characterized in that, The catalyst layer has a porosity of 40%–50% and a gas permeability of 1.5–2.5 × 10⁻⁶. -12 m 2 The proton conductivity is 0.08-0.12 S / cm.

5. The low-platinum, high-stability film electrode according to claim 1, characterized in that, The proton exchange membrane is a perfluorosulfonic acid membrane with a thickness of 50±5μm and an ion exchange capacity of 1.0±0.05mmol / g; The gas diffusion layer is made of carbon paper with a porosity of 70%–80% and a thickness of 150–250 μm; The Ce 0.8 Zr 0.2 The oxygen storage capacity of O2 nanoparticles is 750-850 μmol O2 / g, and the oxygen vacancy concentration is 10. 21 -10 22 cm -3 .

6. A method for preparing a low-platinum, high-stability film electrode, characterized in that, The method for preparing the low-platinum, high-stability film electrode according to any one of claims 1-5 comprises the following steps: (a) MXene preparation: Ti3AlC2 powder was etched with hydrofluoric acid and washed into the eluent. A concentration of <1 ppm yielded an MXene dispersion; (b) MXene functionalization: The MXene dispersion was subjected to radio frequency plasma treatment and ammonia gas was introduced to achieve nitrogen-oxygen co-doping; (c)Ce 0.8 Zr 0.2 O2 nanoparticle synthesis: Ammonia water was added dropwise to a mixed solution of cerium ammonium nitrate and zirconium nitrate to precipitate the precipitate, followed by hydrothermal crystallization and drying to obtain Ce. 0.8 Zr 0.2 O2 powder; (d) Catalyst ink formulation: Mixed functionalized MXene dispersion, Ce 0.8 Zr 0.2 O2 powder, chloroplatinic acid solution and dispersing agent are ultrasonically dispersed evenly; (e) Electrophoretic deposition: Under a nitrogen atmosphere, catalyst ink is loaded onto the surface of a proton exchange membrane to form a catalyst layer; (f) Heat treatment reduction: platinum is reduced by low-temperature heat treatment in a hydrogen-containing atmosphere; (g) Hot-press bonding: The proton exchange membrane with the catalyst layer deposited is hot-pressed together with the gas diffusion layer to obtain a low-platinum, high-stability membrane electrode.

7. The method for preparing a low-platinum, high-stability film electrode according to claim 6, characterized in that, In step (a), the hydrofluoric acid concentration is ≤10wt%, the etching reaction temperature is 40°C, the reaction time is 22-26 hours, and the stirring rate is 250-350rpm; the concentration of the MXene dispersion is adjusted to 4.8-5.2mg / mL after washing. In step (a), the Ti3AlC2 powder is etched and then separated by centrifugal washing at a speed of 9800-10200 rpm and a washing frequency of 4-6 times.

8. The method for preparing a low-platinum, high-stability film electrode according to claim 6, characterized in that, In step (b), the parameters for radio frequency plasma treatment are: ammonia flow rate 50±5 sccm, N2:H2 volume ratio in ammonia (3.8-4.2):(0.9-1.1), radio frequency power 100W, radio frequency 13.56±0.01MHz, cavity pressure 20±2Pa, and treatment time 60 seconds. In step (c), the molar ratio of cerium ammonium nitrate to zirconium nitrate is 4:1, the total metal ion concentration of the mixed solution is 0.45-0.55M; the ammonia droplet acceleration rate is 1.8-2.2 mL / min, the final pH of the droplet is 9.5±0.1; the hydrothermal crystallization temperature is 175-185°C, the holding time is 11-13 hours; and the drying conditions are vacuum drying at 59.5-60.5°C for 11.5-12.5 hours.

9. The method for preparing a low-platinum, high-stability film electrode according to claim 6, characterized in that, In step (d), the solid content of the catalyst ink is 1.0-1.5 wt%, and the pH is 3.0-4.0; the dispersing agent is polyvinylpyrrolidone, which is added at an amount of 0.05-0.15 wt% of the total ink mass, and has a molecular weight of 9500-10500; the ultrasonic dispersion power is 180-220 W, and the total dispersion time is 25-35 minutes. In step (d), ascorbic acid is added to the chloroplatinic acid solution, the molar ratio of ascorbic acid to chloroplatinic acid is 2:1, and the pH of the solution is 3.0-4.0; In step (e), the conditions for electrophoretic deposition are: oxygen content <50ppm in a nitrogen atmosphere, deposition temperature 23-27°C, applied DC voltage 1.4-1.6V, and deposition time 115-125 seconds.

10. The method for preparing a low-platinum, high-stability film electrode according to claim 6, characterized in that, In step (f), the heat treatment atmosphere is a 5% H2 / Ar mixture, the heating rate is 1.5-2.5°C / min, the holding temperature is 80°C, the holding time is 30 minutes, and the temperature during the heat treatment does not exceed 100°C. After step (f), the thickness of the catalyst layer is 8-9 μm; In step (g), the hot-pressing conditions are: temperature 125-135°C, pressure 1.8-2.2MPa, and hot-pressing time 85-95 seconds.

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